The present invention relates generally to dial indicator holders of the type used in setting up or adjusting machines such as milling equipment and the like. More particularly, the present invention relates to a device adapted to be retrofitted to conventional dial or gauge indicator holders for enabling precision vernier adjustments. The invention is believed to be best classified in U.S. Class 248, subclasses 278 or 284.
Dial or gauge indicator holders are well known in the prior art, and a basic dial indicator holder is disclosed in U.S. Pat. No. 3,442,478, issued to N. Parapetti on May 6, 1969. The adjustable dial indicator holder therein shown is adapted to be fitted to the machine tool quill or spindle assembly, and it includes an articulated arm comprising a pair of pivotally interconnected linkages which mount a conventional dial indicator gauge which facilitates dimensional measurement. The typical dial indicator gauge includes a downwardly projecting feeler portion adapted to directly contact the work piece.
The above mentioned device has met with relatively significant commercial success. It is sold under the trademark INDICOL, and it performs a variety of readings for the machinist without disturbing the setup of the quill or spindle of the machine. Machinists may advantageously employ the INDICOL brand dial indicator holders for concentricity positioning of the work piece relative to the spindle center line. Also, the INDICOL brand holder facilitates alignment of the edge of the work piece with longitudinal or transverse movement of the machine table, and it facilitates checking of the perpendicularity of the spindle center line relative to the surface of the table. The INDICOL unit has received wide spread recognition in the field, and its use on a daily basis by modern machinists operating devices such as Bridgeport Mills and the like has been well received. A number of other advantages and uses for the device are discussed in U.S. Pat. No. 3,442,478, which is herein incorporated by reference.
A typical INDICOL brand holder includes a C-shaped collar adapted to be fitted to the spindle, from which the articulated arm extends. The arm comprises a rigid, extension rod pivotally coupled to the C-clamp. The opposite end of the rod is pivotally secured to a rigid linkage which in turn terminates in a pivot coupled to the dial indicator gauge. Thus the unit may be manipulated into a variety of working positions by establishing relative pivoting of the various parts. While the tool may thus dispose the indicator gauge in a variety of positions to aid the machinist, I have found that precision adjustments are very difficult to achieve.
U.S. Pat. No. 4,858,836 issued to Marcyan on Jan. 7, 1975 discloses a bracket assembly which includes a similar articulated linkage associated with a lower dial type indicator gauge. Linkages of this type are also seen in the snap-on holder of U.S. Pat. No. 4,208,157 issued June 17, 1980. A variable length dial test indicator holder is seen in U.S. Pat. No. 4,750,699 issued June 14, 1988. The latter improved dial test indicator is adjustable in length, and because of the multiplicity of pivoted articulate members in the linkage, it may assume a wide variety of operational positions. U.S. Pat. Nos. 1,059,948, 2,940,783, and 3,531,867 are believed relevant to this field as well. U.S. Design patents showing armlike linkages of this general type are seen in U.S. Pat. Nos. D-259,770 issued July 7, 1981, and D-258,726 issued Mar. 21, 1981.
However, with all known devices of which the INDICOL brand unit is the most familiar, minute or fine adjustments to the dial indicator position are very difficult to achieve. When manually manipulating the articulated arm linkages by pivoting adjacent arm members relative to one another, for example, what seem like small manual adjustments to arm position result in gross displacements of the indicator dial face. In other words, the indicator dial often goes off scale. To manipulate the linkage until a mid-range dial reading is achieved with the vernier indicator dial is difficult and time consuming. Therefore, I have proposed a device which may be retrofitted to conventional dial indicator holders of the type disclosed for enabling vernier adjustments to the dial position quickly and easily. While the best mode of the depicted device relates generally to the INDICOL brand unit discussed, its principals can equally be employed by retrofitting to any two articulated arm elements of the various known holder devices.